I would not use sevin dust. I would get some D.Earth and use it it is safer and more effective on mite or lice. It can be feed with there food to help prevent worms and internal parasites. Sprinkle it the area where they dust bath and this will help eliminate pest in the future. Make sure the D.earth is food grade. Can get at TSC very reasonably priced.

Carbaryl is no longer approved for chickens of any age, so don't use it. Permethrin works fine and is approved for use. DE when dry is somewhat effective, but in damp litter won't work, and eaten, has no effect on internal parasites. Any product is bad to breathe, so wear at least a N95 dust mask when using it. Mary